Maintenance release of 0.23

[HeroicKatora]

We want people to transition but not ignoring the history of version bump downstream, we can't expect this. Thus we should port fixes to the previous version. Branch will be based on the prior release.

+1 on another 0.23.x release. Looks like there's been a bunch of additions since the last release; in particular I'd love to see #1624 supported in a version on crates.io (jaredforth/webp#7 (comment) for context).

Originally posted by @antonok-edm in #1433 (comment)

List of PRs to (potentially) port:

• Implement From on DynamicImage #1485
• Add width()/height() to DynamicImage #1493
• Add non-panicking get_pixel/mut methods to ImageBuffer #1500
• Panic in 'copy_from_slice' for BmpDecoder<R>::read_image_data #1502
• Better handling of image size overflows #1510
• webp: Do not panic on overflow if size is maximum #1563
• Added overflow handling to multiplication of width and components #1619
• Optimize decoding of certain RGBA BMP files #1640
• Add new magic byte #1649